[Effect of cold adaptation on the transmission of excitation in a myoneural synapse].

In cold-adapted rats, synaptic excitability of single muscle fibers of fast (m. gastrocneiraus ) and slow (m. soleus) muscles as well as lability of their synapses were studied with the intracellular recording of APs. A decrease of thresholds of the synaptic excitability both in fast and in slow muscle fibers was found in cold-adapted rats. The lability of neuromuscular synapses in both types of muscles was also higher in the cold-adapted rats than in the control group. Cold adaptation seems to induce changes of synaptic transmission of excitation in fast and slow muscle fibers which reduces their excitability difference.